1. Field of the Invention
The invention relates to the field of demulsifiers, and more specifically, to demulsifiers for use with crude oil.
2. Description of the Prior Art
A large portion of crude oil, when extracted from the ground, contains emulsified salt water in smaller or larger quantities. Such emulsions, which occur predominantly as water/oil emulsions, must be separated into their phases, since the salt water contained in the emulsion would interfere with the further processing of the crude oil, especially while it is being transported or distilled.
The separation of such crude oil emulsions is accomplished either by a gravity settling process, by heat treatments, centrifuging, applying electrical fields, the addition of demulsifiers, or by a combination of several of these methods.
However, the extracted crude oil emulsion are generally too stable to be broken by sedimentation, filtration, centrifuging or heating alone. On the other hand, in some cases, demulsifiers, even in small concentrations, cause the emulsion to break.
A large number of demulsifiers have already been proposed. One reason for this is that different crude oils have different compositions and demulsifiers suitable for breaking emulsions of crude oils from one source, are unsuitable for crude oil emulsions from a different location. Known demulsifiers are therefore more or less specific for particular crude oils.
As demulsifiers, alkyl sulfates and alkylaryl sulfonates as well as petroleum sulfonates have already been used in the form of their amine salts. Furthermore, addition products of ethylene oxide and suitable compounds with active hydrogen, such as, alkyl phenols, castor oil, fatty acids, fatty alcohols and aldehyde resins have been used. General information concerning these may be found, for example, in the book "Oberflachenaktive Anlagerungsprodukte des Ethylenoxids" (Surface Active Addition Products of Ethylene Oxide) by N. Schonfeld, Wissenschaftliche Verlagsgesellschaft mbH, Stuttgart, 1959, page 295.